Vapor generating unit



Aug. 5, 1958 A. J. GRAM, JR

VAPOR GENERATING UNIT 2 Sheets-Sheet 1 Filed Oct. 23, 1956 INVENTOR.Arrhur J. GramJr.

ATTORNEY Aug. 5, 1958 A. J. GRAM, JR

VAPOR GENERATING UNIT 2 Sheets-Sheet 2 Filed Oct. 23. 1956 INVENTOR.Arrhur J. Gram, Jr.

ATTORNEY heat exchanger vessel.

United States PatentO VAPOR GENERATING UNIT Arthur J. Gram, Jr.,Alliance, Ohio, assignor to The Babcock '& Wilcox Company, New York, N.Y., a corpo rationof New Jersey Application October 23, 1956, Serial No.617,711

Claims. (Cl. 122-32) This invention relates in general to a vaporgenerating apparatus and, more particularly, to a fluid heated naturalcirculation vapor generating apparatus.

. Vapor generating units are required in many modernday thermodynamicsystems to recover heat or convert energy. Often in these systems theheating source is in the form of a fluid either a liquid, or a highpressure gas or comminuted particles carried by a gaseous mediumcommonly referred to as fluidized. It is a characteristic of thesefluids that they transfer heat at a high rate. Accordingly, vaporgenerating units utilizing such fluids must be capable of withstandinglarge temperature gradients and therefore must be as free as possible ofstresses induced by restrained diflerential thermal expansion.

In some of these processes it is advantageous to have a compact vaporgenerator because the space available in the system into which it mustgo is limited. However, such a compact vapor generating unit must befully cap'able of adequate circulation of the vaporizable medium toassure proper operation.

The present invention directly joins a vapor-liquid separating drum witha vertically arranged U-shaped shell and tube heat exchanger wherebythere is a unitary pressure vessel. This vessel incorporates a heatexchanger and is substantially free of differential thermal stresses,compact in size and is arranged for definite circulation of thevaporizable medium.

For a better understanding of the invention, its operating advantagesand specific objects attained by its use, reference should be had to theaccompanying drawings and descriptive matter in which I have illustratedand described a preferred embodiment of my invention.

Of the drawings:

Fig. 1 is a vertical side section of the invention;

Fig. 2 is a transverse section through the separating drum portion alongthe lines 2-2 of Fig. 1;

Fig. 3 is a transverse section through the heat exchanger portion alongthe lines 3-3 of Fig. 1.

The vapor generator consists of an upper vapor-liquid separating drumdirectly joined to a lower U-shaped shell and tube heat exchanger 12.The heat exchanger has a pressure vessel shell 14 of circular crosssection throughout its length and is arranged in a vertical plane withthe bend portion 16 of the vessel uppermost. At the end of each leg ofthe heat exchanger there are flat tube seats 18, 20 arranged with aplurality of tube seats. Within the vessel 14 there are a multiplicityof small diameter U-shaped tubes formed in a U-shaped tube bundle 22which substantially fills the interior of the Also, as can be seen Withreference to Fig. 3, the cross sect-ionof the heat exchanger throughoutits entire length is substantially uniform. The ends of the tubes of thetube bundle are secured into tube seats of the tube sheets 18 and 2t).Hemispherical heads 24, 26 are attached to the tube sheets 18 and 20respectively to form the fluid chambers 28 and 30. Pipes 32 and 34 arearranged to open into the fluid chambers 28 and 30. These pipes areconnected to a source of the hot 2 fluid so that it may be caused toflow from one chamber through the tubes into the other chamber duringwhich time it would give up heat. Each chamber 28, 30 has a drainconnection 36.

There are four openings 38, 40, 42 and 44 to the lowermost portion ofthe shell sides through which the vaporizable fluid is introduced to theshell side for the generation of vapor therein. Blow-off fittings 46 areabove each of the tube sheets to provide a means for'removing sedimentresulting from the vapor generation. At the uppermost portion of theheat exchanger pressure vessel at the top of the bend 16 there is anopening 48' at which position the vapor-liquid separating drum 10 isdirectly joined to the shell 14.

The separating drum 10 consists of a-vertically elongated pressurevessel 50 of circular cross section having an upper dished head 52 and alower dished head 54 in which there is an opening coinciding with theopening 48 of the lower heat exchanger pressure vessel. The upper vessel10 is integrally joined to the'heat exchanger 12 by welding to result ina unitary pressure vessel consisting of the upper drum and the lowerheat exchanger vessel with free communication between the interior ofthe two vessels. The interior of the upper drum 10 is divided by theupright circular baffle 56, which is joined to the vapor generator attheopening 48, and extends upwardly parallel to the vertical central axisto the upper part of the drum. A circular cover plate 58 is attached tothe'baflie 56 to form a vapor-liquid mixture collection chamber 57,having a plurality of vertically elongated slot openings 60.

trifugally separates the vapor from the liquid with the vapor passing upthrough corrugated type scrubber ele- 'ments 64 and past a distributingplate66 into the upper vapor space 68 of the drum. There it passesthrough a 'dry pan 70 to a vapor outlet 72. The separated liquid fromthe separators is passed into the lowermost portion of the drum from thebottom' of the separators and into an annular liquid space 74. Due tothe arrangement 'the liquid forms a liquid level 76 separating the vaporfrom the liquid space.

I There is an inverted generally conical shaped baflie 78 disposed atthe lowermost portion of the drum spaced from the wall thereof toprevent the discharged separated liquid from thermally shocking thethick pressure vessel wall. A feed -water pipe 80 enters the drumthrough the upper head 52 and extends downwardly along the central axisinto the vapor-liquid collection chamber. By this arrangement theincoming feed liquid is heated up by the condensation of some of'thegenerated vapor before it passes through the vapor-liquid separators.

There are four downco'm'er pipes 82,84, 86, 88 which take the separatedliquid from the lowermost portion of the separating drum and pass itdownwardly into -the'l0w ermost portion of the U-shaped heat exchangeron the shell side. Each of these downcomers are attached at the openings38, 40,42 and 44 in the lower vessel 14.

The vapor generator'as described herein provides a distinct circulationpath for the vapor-liquid mixture to rise to an upper position where itis mechanically separated and the separated liquid to pass downwardlydirectly in the steam generation area. This provides a maximumcirculation and allows the circulating head to be reduced. Theutilization of a low circulation head is further enhanced by the use ofthe whirl chamber type separators which are able to produce relativelymoisturefree steam while utilizing small pressure drops.

By directly joining a separating drum to a U-shaped heat exchanger,there results a vapor generator substantially free of restraineddifferential expansion while the shell of the U-shaped heat exchanger isthiner than would have to be utilized with more conventional type heatexchangers.

While in accordance with the provisions of the statute's I haveillustrated and described herein the best form of the invention known tome, those skilled in the art will understand that changes may be made inthe form of the apparatus disclosed without departing from the spirit ofthe invention covered by my claims, and that certain features of myinvention may sometimes be used to advantage without a corresponding useof other features.

I claim:

1. A vapor generator comprising a vapor-liquid separating drum havingbaflle means dividing its interior into a vaporspace above a liquidspace and a vapor-liquid collection chamber communicating with saidspaces, vapor-liquid separating means arranged in said drum to receivea'vapor-liquid mixture from said collection chamber and to deliverseparated vapor to the vapor space and separated liquid to the liquidspace, said separating means including a ring of hollow upright whirlchamber separators circumferentially spaced to receive individualstreams of vapor-liquid mixture from said chamber, and a U-shaped shelland tube type heat exchanger vertically arranged for steam generation onthe shell side and with its bend uppermost, said heat exchanger directlyand dependently joined to said separating drum for the delivery of thevapor-liquid mixture from both legs of said heat exchanger to thevapor-liquid collection chamber in said separating drum.

2. A vapor generator comprising a vapor-liquid separating drum havingbaffle means dividing its interior into a vapor space above a liquidspace and a vapor-liquid collection chamber communicating with saidspaces,

vapor-liquid separating means arranged in said drum to receive avapor-liquid mixture from said collection chamber and to deliverseparated vapor to the vapor space and separated liquid to the liquidspace, said separating means including a ring of hollow upright whirlchamber separators circumferentially spaced to receive individualstreams of vapor-liquid mixture from said chamber, a U- shaped shell andtube type heat exchanger vertically arranged for steam generation on theshell side and with its bend uppermost, said heat exchanger directly anddependently joined to said separating drum for the delivery of thevapor-liquid mixture from both legs of said heat exchanger to thevapor-liquid collection chamber in said separating drum, and downcomermeans connecting said liquid space of said drum to the lowermost portionof the shell side of said heat exchanger.

3. A vapor generator comprising a vapor-liquid separating drum havingbaflie means dividing its interior into a vapor space above a liquidspace and a vapor-liquid collection chamber communicating with saidspaces, vapor-liquid separating means arranged in said drum to receive avapor-liquid mixture from said collection chamber and to deliverseparated vapor to the vapor space and separated liquid to the liquidspace, said separating means including a ring of hollow upright whirlchamber separators circumferentially spaced to receive individualstreams of vapor-liquid mixture from said chamber, and a U-shaped shelland tube heat exchanger vertically arranged for steam generation on theshell side and with 4 its bend uppermost, said heat exchanger directlyand dependently joined at its uppermost portion to the lowermost portionof said separating drum for the delivery of the vapor-liquid mixturefrom both legs of said heat exchanger into the vapor-liquid collectionchamber in said separating drum.

4. In a vapor generator, a vertically arranged U-shaped pressure vesselof circular cross-section with its bend uppermost, an upper uprightelongated pressure vessel of circular cross section superjacent andjoined at its lowermost portion to said U-shaped vessel at the bend forthe free communication of the interiors of said vessel, a vapor outletfrom said upper vessel, a plurality of tubes constituting a U-shapedbundle disposed within and substantially filling said U-shaped vessel,means including a tube sheet forming fluid collection chambers at theend of each leg of the U-shaped vessel, means connecting the tube endsto the tube sheets for the flow of a heating fluid from one chamberthrough the tubes and into the other chamber, means forming a verticallyelongated vapor-liquid collection chamber in the lower center portion ofthe upper vessel arranged to collect all of the vapor-liquid mixturegenerated in said U-shaped vessel, vapor separating means in said uppervessel arranged to receive and separate a vapor-liquid mixture from saidvapor-liquid collection chamber including a ring of hollow upright whirlchamber separators circumferentially spaced, each separator arranged todeliver vapor to the uppermost portion of the interior of the uppervessel and separated liquid to the lowermost portion thereof, anddowncomer means for delivering said separated liquid to the lowermostportion of each leg of the shell side of said U-shaped vessel.

5. In a vapor generator, a vertically arranged U-shaped pressure vesselof circular cross-section with its bend uppermost, an upper uprightelongated pressure vessel of circular cross section superjacent andjoined at its lowermost portion to said U-shaped vessel at the bend forthe free communication of the interiors of said vessel, a vapor outletfrom said upper vessel, a plurality of tubes constituting a U-shapedbundle disposed with and substantially filling said U-shaped vessel,means including a tube sheet forming fluid collection chambers at theend of each leg of the U-shaped vessel, means connecting the tube endsto the tube sheets for the flow of a heating fluid from one chamberthrough the tubes and into the other chamber, means introducing avaporizable fluid into the lowermost portion of the shell side of theU-shaped vessel for the generation of vapor therein, means forming avapor-liquid collection chamber in the upper shell arranged to collectthe vapor-liquid mixture generated in said U-shaped vessel, vaporseparating means in said upper vessel arranged to receive and separate avapor liquid mixture from said vapor-liquid collection chamber includinga ring of hollow upright whirl chamber separators circumferentialyspaced, each separator arranged to deliver vapor to the uppermostportion of the interior of the upper vessel and separated liquid to thelowermost portion thereof, and downcomer means for delivering saidseparated liquid to the lowermost portion of each leg of the shell sideof said U-shaped vessel.

References Cited in the file of this patent UNITED STATES PATENTS1,416,995 Stroud May 23, 1922 FOREIGN PATENTS 1,043,292 France June 10,1953 690,993 Great Britain May 6, 1953

